The invention relates to a cassette for winding up photographic strip material.
Such cassettes are known in many forms. They are used especially in photographic laboratories in conjunction with copying apparatuses that are automated to a greater or lesser degree and to which they can be coupled in a light-tight manner so that strip material to be wound up, for example exposed photographic paper, can be fed directly to the cassette. The publications DE-OS 2 846 953, DE-OS 3 048 727, DE-OS 3 116 041 and DE-OS 2 939 430 disclose various such types of cassette in the case of which the photographic paper to be wound up is wound onto a winding coil using various means. In the case of the cassettes described in those publications, however, no details are given of the mounting and dismounting of the winding core, or of the slipping on and securing of a sleeve onto which the photographic paper is wound.
A further such cassette is known from DE-PS 3 150 495. In the case of the cassette described in that publication, the strip material to be wound up is wound onto an exchangeable spool component which seats on a rotatably mounted receiving arbor. A pasteboard core having the desired outside diameter can be slipped onto the cylindrical body of the spool component. Provided on both sides of the pasteboard core are flanges which are supported by external rings on the pasteboard core. Those external rings can be connected securely to the cylindrical body of the spool component so that the guiding of the pasteboard core is ensured by the flanges. Such a cassette has the disadvantage that, when winding round the pasteboard core, the friction between the surface of the pasteboard core and the strip material is often insufficient when the strip material is wound up to avoid air gaps being formed between the individual layers of the strip material wound round the pasteboard core. Means that constantly press the strip material against the winding core are not, however, mentioned in that publication. It is also a considerable disadvantage that, when exchanging such a spool component, for example when a winding core has been completely filled with strip material, it is always necessary to exchange the whole spool component with the slipped-on pasteboard core and to insert a new spool component with a pasteboard core placed thereon. In addition, for further processing of a completely full pasteboard core, the latter has also first to be taken off the cylindrical body of the spool component unless there is provided in the downstream processing station a receiving means that is tailored exactly to the dimensions of the receiving arbor on which the spool component seats with the pasteboard core. That entails an additional operation and thus greater use of resources.
Another such cassette is known from DE-PS 3 034 081. In the case of the cassette described in that publication, the strip material to be wound up is guided in a strip channel formed by a link chain which extends round a pasteboard core. Fitted to the end of that link chain is a carrier lever that is rotatable about an axis and on the other lever arm end of which is fitted a roller that presses the strip material to be wound up against the pasteboard core or the strip material already wound onto that pasteboard core. The pasteboard core itself is slipped onto a rotatably mounted hexagonal core. The disadvantage of that cassette is on the one hand that, when exchanging a full pasteboard core, first the link chain which lies around and against the coil, has to be moved away or detached in order to be able to remove the pasteboard core from the rotatable hexagonal core. Furthermore, the slipping on and removal of the pasteboard core is not very easy since the pasteboard core has to seat securely on the hexagonal core in order to be satisfactorily carried along with the rotational movement of the hexagonal core. If, on the other hand, the pasteboard core seats only loosely on the hexagonal core, then it may happen that it is not satisfactorily carried along with the rotational movement of the hexagonal core and thus a build-up of strip material may occur in the cassette since the winding-up operation is interrupted for the period in which the hexagonal core does not carry the pasteboard core along but the strip material continues to be fed into the cassette. On the one hand, therefore, it is essential for the pasteboard core to seat securely but, on the other hand, the core is also to be readily exchangeable.